ray at oneunified.net
Sun Jan 22 23:17:41 UTC 2023
On 1/22/23 16:05, Matthew Petach wrote:
> On Sun, Jan 22, 2023 at 2:45 PM Michael Thomas <mike at mtcc.com> wrote:
> I read in the Economist that the gen of starlink satellites will have
> the ability to route messages between each satellite. Would
> routing protocols be up to such a challenge? Or would it have to be
> custom made for that problem? And since a lot of companies and
> are getting on that action, it seems like fertile ground for (bad)
> Unlike most terrestrial links, the distances between satellites are
> not fixed,
> and thus the latency between nodes is variable, making the concept of
> "Shortest Path First" calculation a much more dynamic and challenging
> one to keep current, as the latency along a path may be constantly
> as the satellite nodes move relative to each other, without any link
> state actually
> changing to trigger a new SPF calculation.
> I suspect a form of OLSR might be more advantageous in a dynamic partial
> mesh between satellites, but I haven't given it as much deep thought
> as would
> be necessary to form an informed opinion.
> So, yes--it's likely the routing protocol used will not be entirely
> but will instead incorporate continuous latency information in the LSDB,
> and path selection will be time-bound based on the rate of increase in
> along currently-selected edges in the graph.
Satellites move constantly relative to each other and to ground stations.
There is a database available which contains the parameters for
calculating a satellite's location at any instant in time.
To maintain minimal link disruption, the idea is to calculate these
relative relationships, and using some graph and network flow
algorithms, you pre-calculate the links and then insert/remove those
links and routes into the routing information base at the appropriate
Then based upon latency, signal quality, and link availability, routing
information is inserted/deleted into the forwarding information base.
There are other contributors such as link saturation and overall
end-to-end delays which could be applied based upon ground station state
It becomes a multi-parameter link selection algorithm in a dynamic
Pretty much an interesting 'sdn' like scenario.
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